Load handling in fork lift trucks

ABSTRACT

A slope-piling arrangement for a fork-lift truck in which one of the lifting forks has its vertical leg movably engaged with the fork apron so that the fork leg, during movement relative to the apron, is constrained to move vertically, and in which a power drive mechanism is connected between the apron and the fork for moving the fork relative to the apron.

United States Patent [191 Melin 1 June 26, 1973 LOAD HANDLING IN FORK LIFT TRUCKS [76] Inventor: Thomas N. Meiin, 1424 24th Avenue, Longview, Wash. 98632 [22] Filed: Feb. 25, 1971 [211 App]. No.2 118,845

Related US. Application Data [60] Division of Ser. No. 801,137, Feb. 20, 1969, Pat. No. 3,589,541, which is a continuation-in-part of Ser. No. 439,846, March I5, 1965, Pat. No. 3,429,470.

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[56] References Cited UNITED STATES PATENTS 2,008,324 7/1935 Grab 2l4/750 2,958,436 11/1960 Skutle et al. 214/750 3,164,405 1/1965 Lul] 214/731 X 3,235,108 2/1966 Drakulich 214/731 Primary Examiner-Gerald M. Forlenza Assistant Examiner-R. Johnson Attorney-Christie, Parker & Hale [57] ABSTRACT A slope-piling arrangement for a fork-lift truck in which one of the lifting forks has its vertical leg movabiy engaged with the fork apron so that the fork leg, during movement relative to the apron, is constrained to move vertically, and in which a power drive mechanism is connected between the apron and the fork for moving the fork relative to the apron.

1 Claim, 10 Drawing Figures Pmmnnmzs ms 3.741.420

SHEET 3 0F 3 czumimi Ma Armmw v5 LOAD HANDLING IN FORK LIFT TRUCKS CROSS-REFERENCE TO R ELATED A PPLICATIONS This application is a division of application Ser. No. 80!,137 filed Feb. 20, 1969, now issued as US. Pat. No. 3,589,54]. Application Ser. No. 801,137 was filed as a continuation-in-part of application Ser. No. 439,846 filed Mar. 15, I965 and issued Feb. 25, I969 as US. Pat. No. 3,429,470.

FIELD OF THE INVENTION This invention relates to fork-lift trucks. More particularly, it relates to apparatus adjustably interconnecting the lifting forks of fork-lift trucks with the fork apron so that a load carried on the forks may be lifted from or deposited on load receiving means angled out of the horizontal with respect to the truck chassis.

BACKGROUND OF THE INVENTION In load handling with fork-lift trucks, the load is supported on a pair of forks which extend forwardly from a vertically movable apron mounted to the front end of the vehicle. Usuallythe load is lifted from or deposited on a foundation or the like defining a load-receiving plane parallel to the surface which supports the truck. Often, however, the surface upon which the load is to be deposited, or from which the load is to be lifted, is not parallel to the floor or other surface which supports the truck. In such cases, the forks cannot be engaged with the load without damaging the load and/or the truck, or the load cannot be deposited without damage to the truck, to the load, or to the load-receiving structure.

This invention provides simple, effective and economic apparatus which adjustably interconnects at least one of the forks of a fork-lift truck to the fork apron for vertical movement of the fork relative to the apron and relative to the other fork. Existing trucks can be modified to receive this apparatus. Moreover, the apparatus can be incorporated readily into the design of a truck during manufacture of the truck. The apparatus has the feature that its use does not increase the "offset of the truck, thereby assuring that the loadhandling capacity of the truck is essentially undiminished. The "offset" of a fork-lift truck is the distance between the center of the front axle of the truck and the front surface of the fork apron. Such apparatus is referred to herein as a slope piling apparatus, As used in this specification and in the appended claims, the term "slope piling apparatus" refers to apparatus by which a fork-lift truck is capable of lifting a load from, or depositing a load on, a surface which is angled, in a direction only transversely of the truck, relative to a surface on which the truck is disposed.

SUMMARY OF THE INVENTION Generally speaking, this invention provides a slope piling apparatus for a fork-lift truck. The fork-lift truck for which the slope piling apparatus is provided includes a chassis, a fork apron mounted for controlled vertical movement relative to the chassis, and a pair of load bearing fork members extending from the fork apron. The slope piling apparatus comprises means mounting one of the fork members for guided move ment vertically of the fork apron, and controllable means operatively coupled between the fork apron and the one fork member for moving the one fork member vertically relative to the fork apron and the other fork.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of the invention are more fully set forth in the following detailed description of the invention presented in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front elevation view of the fork apron of a fork-lift truck equipped with apparatus according to this invention; I

FIG. 2 is a side elevation view of the structure shown in FIG. 1;

FIG. 3 is a fragmentary front elevation view of another apparatus according to this invention and which is claimed in the above-referenced patent;

FIG. 4 is a fragmentary front elevation view, with parts broken away, of still another apparatus according to this invention;

FIG. 5 is a fragmentary side elevation view of another slope piling device according to the invention;

FIG. 6 is a rear elevation view taken along line 6-6 in FIG.- 5;

FlGfTis .a -side elevation view of still another slope piling arrah-gement;

FIG. 8 is a side elevation view of yet another slope piling apparatus;

FIG. 9 is a rear elevation view taken along line 99 in FIG. II; and

FIG. 10 is a fragmentary front elevation view of still another slope piling apparatus.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS FIGS. 1 and 2 show a fork apron 10 mounted for vertical movement to an elevator 11 which is connected to the front end ofthe chassis 12 of a fork-lift truclgfl. The elevator typically includes two pairs of channel membersld, 15. Outer channels 15 are pivoted to the truck chassis by pins 16, and inner channels 14 have their upper ends connected together by a bridge (not shown) and are mounted to channels 15 by rollers (not shown) for vertical movement relative to the outer channels. A hydraulic ram 17 is also connected to the chassis at its lower end and is connected to the bridge at its upper end. A length of chain 18 is connected at one end to the fork apron and passes over a pulley (not shown) mounted to the bridge. The other end of the chain is fixed relative to the chassis. The fork apron carries rollers 19 which are engaged between the flanges of the inner channels to mount the apron to the elevator. As ram I7 is extended, the apron is moved vertically an amount double the extension of the ram. The truck chassis is supported on ground 20 by wheels 21. The detaiis of the elevator and its drive mechanism are not part of this invention which resides in the structure mounting the forkstdescribed below) to the fork apron.

Fork apron 10 includes upper and lower cross members 22 and 23, respectively, side members 24, and vertical intermediate members 25. A pair of fork members 26, 27 are carried by the fork apron. Fork member 26 has a vertical leg 28 and a horizontal leg 29, the latter leg being the fork tine upon which a load is engaged when the truck is in use. Fork member 26 is secured to the fork apron by a horizontal hanger rod 30 mounted to apron upper member 22 and passed through a hole 3] in the upper end of the vertical leg ofthe fork member. Fork member 26, therefore, is not movable vertically relative to the fork apron. The rear surface of the fork member bears against the front face of the apron lower member.

A conventional fork-lift truck usually has two fork members generally like those described above, both of which normally are secured to a fork apron in the same manner that fork member 26 is secured to apron 10, or in an equivalent manner. Those skilled in the art, how ever, will readily appreciate that the manner in which fork member 26 is connected to apron I is not a part of this invention, and is described above merely for the purpose of a complete explanation of the invention.

Fork member 27, however, is mounted to the fork apron for movement vertically relative to the apron. This fork member has a vertical leg 32 and a horizontal leg or tine 33 like fork member 26. The upper rear portion of vertical leg 32 defines a boss 34 through which is formed a vertically elongated slot 35 extending paral lel to the front surface of the leg. Hanger bar 30 passes through the slot and cooperates with the slot to guide the fork member in vertical movement relative to the apron.

The slope piling apparatus also includes means for moving fork member 27 vertically relative to the fork apron. A hydraulic ram assembly 36 has one end pivotally connected to lower apron member 23 and its other end disposed between and pivotally connected to a pair of lugs 37 secured to the rear side of vertical fork member leg 32 adjacent the lower end of boss 34. The ram preferably is a double acting ram and is operated by hydraulic fluid supplied to the ram assembly through ducts 38 and 39. The nature of fluid flow through the ducts is controlled by the operator of the truck, thereby controlling the operation of the ram. It will be readily apparent to those skilled in the art that mechanisms different from that described, for example, a jackscrew, may be used to move the fork member vertically relative to the fork apron.

HO. 3 illustrates another form which structure according to this invention may take. A fork member 40 has a vertical leg 41 and a horizontal leg or load bearing line (not shown). The upper rear portion ofthe vertical leg defines a boss (not shown in FIG. 3 but similar to boss 34 shown in FIG. 2 as a part of fork member 27) through which extends a vertically elongated slot 42. The slot traverses the boss parallel to the front surface of the fork member vertical leg. A horizontal hanger bar 43 extends through slot 42 and has its ends sup ported in a pair of vertical members 44 in a fork apron 45. The fork apron also includes an upper transverse member 46 to which vertical members 44 are connected. The upper transverse member of the fork apron has an aperture 47 formed through it above the fork member. The aperture is large enough to permit the upper end of the fork member vertical leg to be moved through it. Aperture 47, slot 42 and hanger bar 43 cooperate with each other to guide the fork member in vertical movement relative to the fork apron.

An elongated vertical notch 48 is formed in the upper end of fork member vertical leg 4| and extends from front to back of the leg A hydraulic ram assembly 49 is disposed in the notch and has one end secured to the fork member The other end ofthe ram assembly IS secured to a sleeve 50 which journals the hanger bar in notch 48. The ram IS operated to move the fork men ber upwardly and downwardly relative to apron 45. Motive fluid is supplied to the ram assembly through ducts (not shown) which connect the ram assembly to a suitable control at the truck operators station.

FIG. 4 shows yet another structural arrangement of slope piling apparatus according to this invention. Fork apron 52 includes a transverse upper member 53, a pair of vertical members 54 secured to the upper member, and a cross member 55 disposed below the upper member and extending between and secured to'the vertical members. A fork member 56 has a vertical leg 57 and a horizontal leg or tine (not shown). The upper end of the fork member vertical leg has a hole 58 formed through it from side to side of the leg parallel to the forward surface of the leg. The hole is horizontal and receives a hanger rod 59, the ends of which extend laterally of the fork member. The ends of the hanger rod are slidably received in respective ones of a pair of vertically elongated slots 60 formed through the apron vertical members adjacent the apron upper member. The hanger rod and slots 60 cooperate to guide the fork member in vertical movement relative to the fork apron.

A hydraulic'ram assembly 61 is coupled between the fork apron and the hanger rod. One end of the ram assembly, preferably cylinder 62, is secured to apron cross memberSS. The other end of the ram assembly, preferably the outer end of piston 63, is connected to a yoke member 64 which extends from adjacent one side of the fork member vertical leg around behind the leg to the other side of the fork member as shown in FIG. 4. The ends of the yoke member are secured to re spective ones of a pair of sleeves 65 which journal hanger rod 59 between the fork member and apron vertical members 54. Operation of the ram assembly is produced by hydraulic fluid supplied to the ram assembly through supply ducts 66 and 67 at the control ofth operator of the truck. r

Preferably the apron cross member defines therein a forwardly opening notch 68 which has a width slightly' greater than the width of the fork member vertical leg. Notch 68 provides a further guide mechanism for the fork member as it is moved vertically relative to the fork apron in response to controlled operation of ram assembly 6!.

FIGS. 5-10 illustrative other embodiments of slope piling mechanisms according to this invention. FIGS. 5 and 6 show a fork apron 70 to which one fork member 71 is mounted for vertical movement relative to a second fork member (not shown) which may be mounted to the apron in any manner desired, such as the manner in which fork member 26 is mounted to apron l0. Fork member 7] has a load supporting horizontal leg 72 and a vertical leg 73 which is movably engaged for guided movement in a vertical passage 74 defined by the apron. ln the vicinity of the movable fork member, the apron has a front plate 75', a back plate 76 and laterally spaced spacer plates 77.and 78, the latter extending vertically of the apron between the front and back plates. Plates 75-78 define the boundaries of passage 74 which has a cross-sectional configuration conforming to that of the vertical leg of the fork member and which is sized to loosely receive and yet adequately guide the vertical leg. A power drive mechanism 79 is coupled directly between the apron and the fork memher for moving the fork member vertically relative to the apron, the capacity of the drive mechanism is suffcient to move the fork member even when the movable fork member cooperates with the other fork member to support a load up to and equal to the rated load capacity of the forklift truck of which apron 70 is a component. As shown in FIGS. 5 and 6, the drive mechanism preferably is a double acting hydraulic ram 80 pivotally connected between a lug 81 secured to the rear surface of back plate 76 and a lug 82 secured to the rear of the vertical leg of the fork member adjacent the junction between the vertical and horizontal legs of the fork member. The ram is connected to the hydraulic control system of the fork-lift truck by suitable hydraulic lines 83 and 84 so that, upon actuation of the rain in the appropriate direction, the fork member is driven in guided movement relative to the apron. To maximize the guiding engagement of the apron with fork member leg 73 and also to maximize the range through which the fork member may be moved relative to the apron, a downwardly open slot 85 is formed in the lower edge of back plate 76 centrally between spacer plates 77 and 78 to accommodate lug 82.

FIG. 7 is a side elevation view of a slope piling arrangement which is similar to that shown in FIGS. 5 and 6, but in which apron 90 does not define an enclosing passage for the vertical leg 91 of a fork member 92 which also has a load supporting horizontal leg 93. Apron 90 includes a pair of spacer plates 94 and 95 which are arranged similar to spacer plates 77 and 78 of apron 70; the front and rear edges of the spacer plates lie forwardly and rearwardly, respectively, of the corresponding surfaces of the fork member vertical leg, as shown. A front keeper bar 96 is connected between spacer plates 94 and 95 adjacent the upper extent of the apron to slidably engage and constrain the front surface of the fork member vertical leg. A rear keeper bar 97 is connected between the spacer plates adjacent the lower extent of the apron to slidably engage and constrain the rear surface of fork leg 91. Plates 94 and 95 and keeper bars 96 and 97 define an open passage along which the vertical leg is guided when a drive mechanism, such as a double acting hydraulic ram 98 having supply lines 99 and 100, is operated. Ram 98 is connected between a lug 101 secured to the upper rear extent of the vertical leg and a lug 102 secured to the rear surface of rear keeper bar 97. The capacity of ram 98 should be as described concerning ram 80.

It will be apparent that, regardless of whether a load is supported by the horizontal leg of fork member 92, the fork member, by reason of its own weig'htjand ge ometry, engages the front and rear keeper bars in the manner indicated by the arrows in FIG. 7. Thus, the described structure is effective to both support and guide the fork member during use of the fork-lift truck of which the apron is a component. It will also be seen that ram 98 is connected between the apron and the movable fork member in such manner to maintain and even augment proper engagement of the fork member with the keeper bars.

The embodiment shown in F1088 and 9 includes front and rear keeper bars I05 and 106 which are secured to the front and rear surfaces of the vertical leg 107 ofa fork member 108 having a horizontal load supporting leg 109. Vertical leg l07 cooperates within a vertical passage 111 formed within apron 0 which has a back plate ll2 having a rear surface substantially coplanar Alll'l lllL' rear surface of the vertical leg, the apron has a front plate (not shown), the front surface of which is substantially coplanar with the front surface of vertical leg 107 on opposite sides of the passage. The keeper bars extend laterally in opposite directions of the sides of the fork member vertical leg to slidably engage the exterior surfaces of the apron front and back plates and to transfer the loads of and applied to the fork member to the apron. A double acting hydraulic ram 114, comprising power drive means for the slope piling mechanism shown in FIG. 9, is connected between lugs 115 secured to the lower rear extent of vertical leg I07 and a-bar 116 which extends parallel to the back plate and is supported on opposite sides of the passage by lugs 117 secured to the back plate. Ram 114 is connected to the fork-lift truck hydraulic system by suitable hydraulic lines 118 and 119. Upon application of a load W (FIG. 8) to the fork member, the keeper bars are forceably engaged with the apron as shown by the arrows in FIG. 8. The embodiment shown in FIGS.

8 and 9 operates according to much the same set of principles as are applicable to the operation of the embodiments shown in FIGS. 5-7.

The embodiments described above and shown in FIGS. 1-9 involve, in basic terms, structure in which only orie oftwo load handling fork members is vertically movablcirelative to a supporting elevatable apron; it will be appreciated, however, that both forks may be movable vertically relative to the apron without depart ing from the scope of the invention. The embodiment shown in FIG. 10 provides two vertically movable forks which are interconnected to move simultaneously equal amounts in opposite directions upon operation of the power drive mechanism associated with the forks.

Thus, as shown in FIG. 10, a pair oflifting fork mem bers and 126, each having a vertical leg 127 and a horizontal leg 128, are associated with an elevatable fork apron 129 in a fork-lift truck, such as truck 13. The forks are disposed forwardly of an apron'fropt plate 130 and are located adjacent the left and tight ends of the apron as viewed in FIG. 10. Each fork is engaged with a separate hanger bar 131 and 132 in the manner described above relative to fork 26. The hanger bars are supported at their juxtaposed ends in corresponding ones of a pair of support blocks 133 and 134 secured to the apron front plate. The bars cooperate in oversized holes 135 formed through the blocks. The adjacent ends of the bars define rounded heads 136 which may abut each other as shown in FIG. 10.

The opposite ends of each of the hanger bars, outwardly of the corresponding fork member, carry a roller 138 which is engaged with a bearing plate 139 secured to the apron, preferably in the adjacent upper corner of the apron. A suspension link 140 is associated with each hanger bar and has its lower end connected to the bar, preferably between the corresponding fork member and the corresponding roller. The other end of each suspension link is pivotally connected to a corresponding bellcrank 142, the bellcranks being spaced from each other along'the: length of the apron and pivotally mounted to the apron at 143 and 144, respectively. The bcllcranks are pivotally interconnected by a connecting rod 145.

A drive mechanism 147, such as a double acting hydraulic rant 148 having suitable hydraulic lines I49 and 150 connecting it to the hydraulic system of the fork lift truck. is connected between one of the bellcranks and the apron for driving the forks upwardly and downwardly relative to the apron. Operation of the drive mechanism, because of the arrangement of the bellcranks as shown in FIG. 10, causes forks 125 and 126 to move equally in opposite directions relative to the apron, thereby to controllably adjust the angular relation of a load supported on the forks relative to the apron about an axis normal to the apron front plate. During such movement of the forks, the hanger bars pivot relative to the apron about pivot points 151, and the rollers roll along bearing plates 139.

The utility of slope piling apparatus according to this invention is apparent from the following description of the operation of the embodiment shown in FIGS. 1 and 2, Let is be assumed that the fork-lift truck is supported on a horizontal surface such as ground 20, and that fork member 27 is positioned so that its horizontal leg is dis posed in the same horizontal plane as the horizontal leg of fork member 26. This is the usual position of the vertically movable fork member. Let it also be assumed that the operator of the truck desires to engage the fork tines under a pallet upon which a load is supported so that the loaded pallet can be lifted and moved by the truck, but that the pallet is resting on a surface which is inclined to the horizontal across the truck at an angle A (see FIG. 1), which is of such magnitude that both forks cannot be engaged under or within the pallet. If the truck were moved forward in an attempt to engage the forks with the pallet, one or the other or both the fork members would engage the pellet structure, the load on the pallet, or the structure upon which the pallet is supported; such engagement of the forks with any of these things would damage the structure so engaged and might damage the truck itself. To avoid this result, the operator of the truck merely operates ram 36 to raise or lower the movable fork member an amount sufficient to locate both fork members in a plane parallel to the surface on which the pallet is supported; vertical correspondence of these planes can be achieved by raising or lowering the fork apron. The forks can then be engaged with the pallet with ease, and the pallet can then be lifted and placed in a horizontal condition by returning the movable fork member to its normal position.

If a load supported on the fork members is to be deposited on a surface which is inclined across the truck relative to the surface on which the truck is supported, the process described above can be reversed. It is pre ferred that the forks be placed in a plane parallel to the surface upon which the load is to be deposited before the apron is lowered so that the weight of the load will be uniformly distributed over the receiving structure as the load is deposited. If a conventional fork lift truck having forks fixed vertically relative to the fork apron were used in the situation described, the forks could not be withdrawn from under the load without damage to the load, to the load receiving structure, or to the forks As indicated above, the vertically movable fork member in slope piling apparatus according to this invention normally is positioned at the midpoint of its range of vertical movement relative to the fork apron; the structure for moving and for guiding the movable fork member is arranged so that the tine of the movable fork member is then disposed in the same horizontal plane as the tine of the other fork member, assuming the truck itself is horizontal. Such a normal position of the movable fork member enables the fork to be moved either up or down as required. This normal position of the movable fork member also means that only a single movable fork is required to provide a truck capable of lifting or depositing loads on surfaces inclined either way across the truck relative to the surface on which the truck itself is located. Obviously, however, as shown in FlG. 10, the truck could be provided with two vertically movable forks, which forks may or may not be operatively interconnected as shown in FIG. 10.

The invention has been described above in the context of specific types of mechanisms and structural arrangements. Workers skilled in the art to which the invention relates will recognize that modifications and alterations may be made in the mechanisms and structures described without departing from the spirit of the invention. Accordingly, the foregoing description is not to be considered as limiting the scope of this invention.

What is claimed is:

l. Slope piling apparatus for a fork-lift truck having a fork apron extending transversely of the length of the truck forwardly of a chassis of the truck and a pair of load bearing forks carried by the apron and extending forwardly from the apron, one ofthe forks having a vertical leg and a horizontal leg, the slope piling apparatus comprising means mounting the vertical leg of the one fork to the apron for guided movement vertically relative to the other fork including a vertical passpge defined by the apron for cooperating with the one fork vertical leg to constrain the vertical leg from movement laterally of its length and to guide the vertical leg along a substantially linear path relative to the apron, means arranged with regard to the reaction of loads applied to the one fork and cooperating between the one-fork vertical leg and the apron for constraining the fork from moving out of the passage in directions normal to the apron and for further guiding the one fork vertical leg in movement along said path, the constraining and further guiding means including a forward keeper member fixed to the forward surface of the vertical leg adjacent the lower end thereof and extending laterally of the vertical leg for engagement with the apron laterally of the passage, and a rear keeper member fixed to the rear surface of said vertical leg adjacent the upper end thereof and extending laterally of the vertical leg for engagement with the apron laterally ofthe passage, and controllable power means coupled to the apron and to said vertical leg for moving the one fork vertically along said path relative to the apron.

a c o a o 

1. Slope piling apparatus for a fork-lift truck having a fork apron extending transversely of the length of the truck forwardly of a chassis of the truck and a pair of load bearing forks carried by the apron and extending forwardly from the apron, one of the forks having a vertical leg and a horizontal leg, the slope piling apparatus comprising means mounting the vertical leg of the one fork to the apron for guided movement vertically relative to the other fork including a vertical passage defined by the apron for cooperating with the one fork vertical leg to constrain the vertical leg from movement laterally of its length and to guide the vertical leg along a substantially linear path relative to the apron, means arranged with regard to the reaction of loads applied to the one fork and cooperating between the one fork vertical leg and the apron for constraining the fork from moving out of the passage in directions normal to the apron and for further guiding the one fork vertical leg in movement along said path, the constraining and further guiding means including a forward keeper member fixed to the forward surface of the vertical leg adjacent the lower end thereof and extending laterally of the vertical leg for engagement with the apron laterally of the passage, and a rear keeper member fixed to the rear surface of said vertical leg adjacent the upper end thereof and extending laterally of the vertical leg for engagement with the apron laterally of the passage, and controllable power means coupled to the apron and to said vertical leg for moving the one fork vertically along said path relative to the apron. 